Coating of polymers with titanium-based layers by a novel plasma-assisted chemical vapor deposition process

Chemical vapor deposition (CVD) is an excellent technique to coat complex s ubstrates like fibers or inner surfaces of tubes. However, CVD often suffer s from high coating temperatures which makes it impossible to coat temperat ure-sensitive materials like polymers, e.g. with titanium-based layers. A n ew plasma-assisted CVD (PACVD) process has been developed to coat polymers at very low temperatures with titanium-based layers. The coating temperatur e could be lowered to approximately 60 degreesC (140 degrees F), so that a variety of different polymers can be coated without undesired damaging. In this work, polyethylenetherephthalate (PET), polyethersulfone (PES), polyvi nylchlorine (PVC), polytetrafluoroethylene (PTFE), polyethylene (PE) and po lypropylene (PP) have been used. Very smooth (R-a = 3 mm) and thin (5-100 n m) layers show a very good adherence (>10 N/mm(2)) when examined using tens ile tests. It could be demonstrated that all kinds of geometries such as tu bes or textile structures can be coated. The coating has the huge potential to improve the bio- and bloodcompatibility of polymers for medical devices . This could be shown by a significant higher cell vitality and growth of t he cells on Ti(C,N)-coated polymers compared with uncoated polymers (using fibroblasts and endothelial cells). Moreover, the coagulation of blood is l ess effected if polymers are coated with the Ti(C,N) layers. It could be de monstrated, that the Ti(C,N)-coating is an effective diffusion barrier to p revent leaching of plasticizers or additives, e.g. from PVC which is advant ageous for many medical devices as well as for a lot of other applications where PVC is used. Besides the medical applications many other improvements of polymers are possible by this new coating process. Examples are surface s with a higher wettability, corrosion stability or electrical conductivity . (C) 2000 Elsevier Science B.V. All rights reserved.